Gyroscopically controlled electrical gun sight



Oct. 9, 1951 P. R. WHEELER GYRoscoPIcALLY CONTROLLED ELECTRICAL GUNSIGHT 4 Sheets-Sheet l Filed Dec. 19, 1945 u INVENTOR PHlLL/P R. WHEELERj BY W ATTOR NEYS Get. 9, 1951 P. R. WHEELER GYROSCOPICALLY CONTROLLEDELECTRICAL GUN SIGHT 4 Sheets-Sheet 2 Filed Deo. 19, 1945 ATTORNEYS R ME E mw m w E m m R P O GE NnU. .HT lm n w mm P Q .uw m 0 Y 5 B ...IlII." Il 7 2 u w.

TO'H'DEFLECTING PLATE 0F CR TUBE Oct. 9, 1951 P. R. WHEELERGYRoscoPIcALLY coNTRoLLED ELECTRICAL GUN SIGHT Filed Dec. 19, 1945 4Sheets-Sheet 5 INVENTOR PH/LL/P R WHEELER /MMA ATTORNEYS C. 9, 1951 p R,WHEELER 2,570,298

GYROSCOPICALLY CONTROLLED ELECTRICAL GUN SIGHT Filed Dec. 19, 1945 4Sheets-Shea?l 4 mvENToR PH/LL/P l?. WHEELER /ZMM'M BY @fm1-renewPatented Oct. 9, 1951 UNITED STATES PATENT OFFICE GYROSCQPICALLYCONTROLLED ELECTRICAL GUN SIGHT (Granted under the act of March 3, 1883,as amended April 30, 1928; 370 O. G. 757) 6 Claims.

The present invention relates to electrical gun sights and particularlyto a novel and improved electrical gun sight of the type which does notrequire a stabilized supporting reference plane.

This application is a continuation-in-part of my copending patentapplication,` Serial No. 510,403, entitled Cathode Ray Gun Sight andlled in the United States Patent Ollice on November l5, 1943 nowabandoned. In my copending patent application Serial No. 636,047entitled Cathode Ray Tube Gun Sight and filed in the United StatesPatent Oilice on December 19, 1945, now Patent 2,459,206 granted January18, 1949, claims are addressed to those features of my improvedgun sightwhich are disclosed in Fig. 6 herein.

My invention is of particular utility as embodied in gun sightsoperating on the disturbedline-of-sight principle. Sights of thisgeneral character are described in the following United States Patents:1,322,15'3, J. S. Wilson and W. E. Dalby, issued November 18, 1919;2,183,530, Robert Alkan, issued December 19, 1939; 1,724,093, RobertKauch and Charles L. Paulus, issued August 13, 1929.

When a gunner establishes a line of sight on a moving target he mustlead the target by a suitable angle. That is, the weapon must be sopointed that the line of re leads the line of sight. Otherwise theprojectile would fall behind the target. The lead angle depends on thetarget velocity and the time of flight of the projectile. This leadingis accomplished by the target velocity corrections of the sight setting.The gunner must allow for the effect of gravity on the projectile. Inother words, he must elevate the gun above the direct line of sight tothe target to allow for the drop of the projectile after it leaves thegun muzzle. This is accomplished by the Superelevation corrections ofthe sight setting. Superelevation is functionally related to range andit varies as the cosine of elevation. ln gun sights which operate on thedisturbedline-of-sight principle the gunner maintains the line of sighton a target by tracking the target as he manually positions the gun andsight. The lead angle or target velocity corrections and thesuperelevation corrections furnish a basis for angularly so disturbingthe line of sight with respect to the line of fire that when the line ofsight is maintained on the target the line of re is appropriate to scorea hit.

It is an object of the present invention to provide an improved andsimple electrical arrangement for automatically applying target velocityand Superelevation corrections to a gun sight of the type having adisplaceable reference mark, in such a manner that the accuracy of thesight is not appreciably affected by roll, pitch, yaw or linearacceleration of the ship or other supporting frame on which the gun ismounted.

For a better understanding of the present invention, together with otherand further objects thereof reference is made to the followingspecication, to the claims appended thereto and to the accompanyingdrawings, in which:

Fig. 1 comprises a geometrical presentation of the lead anglecomputation;

Fig. 2 comprises a geometrical presentation of the Superelevationcomputation;

Fig. 3 comprises a perspective View of the gyroscopic control mechanismsincluded in my improved sight;

Fig. 4 and Fig. 5 comprise perspective views of a gun and mount showingmy improved gun sight in place; and

Fig. 6 comprises a sectional View of the cathode ray tube arrangementfor providing a displaceable reference image or mark, including aschematic showing of the arrangements for displacing the mark.

Fig. 1 shows the essential features of the shortrange re controlproblem. A gun Il is fired at an airplane I2. At the instant of i-lrethe airplane is in a position called the present position. The gunshould be pointed at some later or predicted position of the targetcalled the future position, such that the projectile will reach thefuture position at the same time as the target. The angle between theline from the gun to the present target position or (line of sight) andthe line from the gun to the future position (or line of fire) is thelead angle.

The angular velocity of the target as observed from the gun is theangular movement of the target about the gun per second of time. Thetime of flight is the time taken by the projectile to reach the target.The total angular motion of the target (or lead angle) during the timeof ilight is equal approximately to the angular velocity of the targetat the present position multiplied by the time of flight in seconds.Other quantities involved in the lead-computing lire control problem,such as present and future slant range, are appropriately labeled inFig. 1.

If the gun bore were pointed at the future position of the targetwithout further correction the projectile would then fall below thetarget because of the downward force of gravity. To compensate for thisundesired effect of gravity the gun elevation is increased by anadditional angle called the superelevation angle as illustrated in Fig.2. The superelevation angle required is dependent upon (a) theballistics of the gun and projectile, (b) the time of flight of theprojectile to the target, (c) the cosine of the angle of gun elevation.The ballistics of any given gun can be considered constant over shortranges and therefore the superelevation angle is calculated with thereasonable approximation according to the following equation:

Superelevation constant time of flight cosine of gun elevation.

The above mentioned United StatesPatent No. 1,322,153 discloses meansfor establishing a line of sight and electrical-generator-means forangularly disturbing the line of sight with reference to the lgun boreaxis or line of fire by an amountfunctionally related to the rates oftracking of a target in train and in elevation, whereby the line ofsight is disturbed by an amount functionally related to the speed of thetarget so that the proper lead angle is introduced when the gunnermaintains the line of sight on a target by swinging the gun in elevationand in azimuth. This sighting arrangement is premised on the functionalrelationship which exists between target velocity and tracking rate whenthe gun is mounted on a stable reference or supporting frame. However,when the gun and sight are mounted on a supporting frame (such as thedeck of a ship) which is subject to roll, pitch, yaw and linearacceleration, the functional relationship between this relative motion(between gun and supporting frame) and velocity of the target no longerholds. Further the functional relationship between the relativepositions (of the gun and supporting frame) and the elevation ,of thetarget no longer holds. Therefore, these factors (rolls, etc.) introduceerrors in both the target velocity and superelevation corrections. Eachof the generators disclosed in United States Patent No. 1,322,153measures a rate of motion of the gun relative to the supporting frame.In accordance with my invention I provide gyroscopic arrangements fordisturbing the line of sight and I measure the absolute rate of motionor tracking rate of the gun relative to an imaginary fixed or stableframe of coordinates.

In Fig. 4 there is illustrated, in combination with a universal gunmount I3 carrying a gun II for movement in elevation and in azimuth, anovel sighting arrangement generally indicated at I5. This arrangementcomprises the elements included within the housings indicated at I6, I1and I8. Housings I6 and I1 are secured to the gun and move with it inelevation and in azimuth as the operator, in using handles I9 and 23swings the gun and sight in tracking a target. Housing I8 is mountedinside the stand 22 (Fig. This arrangement comprises means forestablishing a line of sight as indicated at I6 and specically shown inFig. 6. The cathode ray sighting arrangement illusItrated in Fig. 6 isclaimed in my copending patent application Serial No. 636,047 entitledCathode Ray Tube Gun Sight and filed in the United States Patent Oiiceon December 19, 1945. Thisy sighting arrangement includes a cathode raytube 23 for providing an electrically displaceable reference image ormark. The tube is mounted in a cylindrical housing 24 by means ofsuitable positioning elements 25 and 26. The tube is connected by meansof a cable 21 to the electrical units within housing I8. The cylindricalhousing 24 is attached by screws or other suitable means to the lowerend of the main housing I6 which has an opening 28 at the point ofattachment. A reecting mirror 29 is located in the lower end of thehousing I6 at an angle of approximately 45 degrees to the horizontal.Pivoted to the upper end of the housing I6 is a semi-reflecting flatglass plate 30 which is inclined at anv angle of approximately 45degrees to the horizontal and which may be lifted upwardly on a pivotfor purposes of cleaning the inside of the housing. A suitable catch 3|is provided for holding the glass 30 in position. In the upper end ofthe rear wall of the housing I6 is an opening 32 which providescommunication between the interior of housing I6 and the interior of theeye-piece support 33, which is attached to the housing by means ofscrews or other suitable means. A rubber eye piece 34 and a peep 35 aremounted on a tube 36, which is slidably mounted in the outer end ofsupport 33, theposition of the tube in the support being adjusted bymeans of a spring-pressed plunger 31, which cooperates with notches 38on the tube. A mounting bracket 39 or other suitable expedient isattached to the front wall of the housing I6 in order to provide meansfor mounting the unit securely on the gun.

The cathode ray tube employed in the sight is a conventional type havinga suitable electron gun structure for projecting an electron beam fromits cathode onto a flourescent screen 4I. Vertical and horizontal pairsof electrostatic beam deflecting plates are provided in the tube forpositioning the electron beam, as is common practice in the cathode raytube art. Plates 43' and 44 are grounded (Fig. 6) and plates 45 and 46are connected to sliding contacts 48 and 41 (Fig. 3), respectively. Thecircuit from plate 46 proceeds through conductor 49, one of theconductors 50 of cable 21, conductor 5I and one of the conductors 52 ofcable 53 to contact 41. The circuit from plate 45 proceeds throughconductor 55, one of the conductors 56 of cable 21, Yconductor 58 andone of the conductors 59 of cable G to sliding contact 48.

In the cathode ray tube of the sighting arrangement illustrated in Fig.6 an image such as a spot or circle is formed on the screen 4I and isreflected upwardly by mirror 29 and rearwardly by the semi-reilectingpiece of glass 30 to the eye of the gunner positioned behind the rubbereye-piece 34. The gunner looking into the sight through the rubbereye-piece sees the image of the spot or circle created by the cathoderay tube and reflected by the optical elements 29-30 into the sight lineand at the same time views the target through this piece of glass 30.The gun is aimed by centering or effectively superimposing the reflectedimage as a sighting reference on the target. By means of the electricalcontrols for the cathode ray tube which are presently described, theimage on the tube screen is moved about to provide the variouscorrections. Movement of the image on the screen produces acorresponding movement o f the image or reference reflected into thegunners sight line by the optical elements 29--30 so that a new line ofsight is established to enable the gunner to adjust the position of thegun to correspond to the sighting corrections put into the cathode raytube.

Due to the f act that the line of sight is dened by the image reected by the optical elements 29-30 into the Opraters field pf View and by thepeep located in the rubber eye-piece the amount of correction of theline of sight by a given movement of the image depends upon the positionof the peep in the eye piece with relation to plate 30. The rubber eyepiece and the peep are shown adjustable so that this correction can becalibrated by movement of the eye piece and the peep in and out of thesupport 33.

In attaching the cathode ray tube unit to the gun, the unit I 6 isconveniently placed as near the trunnions of the gun as possible so thatthe eye of the gunner may remain on approximately the same height forall anglesof elevation of the gun. In Figs. 4 and 5 the cathode ray unitI6 of the type shown in Fig. 6 is shown mounted on an antiaircraitmachine gun.

Referring now specifically to Fig. 3 there are illustrated thegyroscopic arrangements for controlling the position of the referenceimage provided by the cathode ray tube 23. These gyroscopic controlsautomatically control the position of the reference mark and disturb theline of sight so that the line of lre established by the sight will leadthe line of sight by an amount proportional to the angular rate ofmovement of the gun with respect to an imaginary fixed or stablereference in space in following the target. Mounted within the housingI1 are a train or azimuth rate gyro unit 62 and an elevation rate gyrounit 63. The train gyro unit measures the rate of the train component ofangular movements of the gun and causes the output voltage of train orazimuth potentiometer 65 to be representative thereof. Similarly, theelevation gyro unit 63 measures the rate of elevation component ofangular movements of the gun and causes the output voltage of elevationpotentiometer 66 to be representative thereof.

The train gyro unit 62 comprises a gyro wheel 61 mounted for spinning ona shaft 68 journaled in a gimbal frame 69. This frame has a shaftextension 10. Rigidly secured to' extension 10 are knife edges 1I and12. The arrangement of elements 61 to 12, inclusive, is such that rangesprings 13 and 14 tend to restrain gyro Wheel 61 so that it will spin inthe plane of elevation. The gyroscope unit 62 is mounted in a casing 15secured by appropriate means (not shown) to housing I1. Similarly, theelevation gyro unit 63 comprises a gyro wheel 11, a shaft 18, a gimbalframe 19, a shaft extension 88, knife edges BI and 82 and range springs83 and 84, inclusive, so arranged that the restraining inuence ofsprings 83 and 84 tends to restrain the gyro wheel 11 so it will spin inthe plane of train. The gyro Wheels are actuated by any suitable meanssuch as air jets (not shown) Shaft extension of unit 62 is secured to alever 85 which lever includes the knife edges 1I and 12 and a suitablyinsulated sliding contact 98 on the voltage divider 65. Likewise, shaftextension 80 of unit 63 is rigidly secured to a lever 81 which includesknife edges BI and 82 and a suitably insulated sliding contact 41 onpotentiometer 66.

Potentiometer 65 comprises an insulating form 89 rigidly secured tohousing I1 by any suitable expedient (not shown). Wound on form 89 is aresistor 90 which is connected by conductors 9| and 92 to the outputterminals of any suitable voltage source 93. As lever 85 causes contact48 to move along resistor portion 90, that portion of the potential ofbattery 93 which exists between slidingcontact 48 and ground is applied,through conductor 59, to deflecting plate 45 of cathode ray tube 23.Similarly, potentiometer 66 comprises an insulating form 94, rigidlysecured to housing I1 by any suitable expedient (not shown). On the formis wound a resistor 95 the terminals of which are connected byconductors 96 and 91 to a battery 98. The arrangement of potentiometer66 is such that the voltage between contact 41 and ground is applied,through conductor 52 to vertical deeeting plate G6 of tube 23.

Wheel 61 of the train gyro unit 62 precesses Whenever the housing I1 ismoved by absolute movement of the gun in train. Additionally, Wheel 11of elevation gyro unit 63 precesses when the housing I1 is movedabsolutely in elevation with the gun. Units 62 and 63 are so arrangedthat the Drecession of each gyro wheel is proportional to the rate ofangular motion of the gun in train or in elevation, as appropriate. Theprecession or deflection of the gyros causes changes in the positions oflevers 85 and 81 and appropriate changes in the positions of contacts 98and 41, with the result that voltages applied to the deilecting platesof the cathode ray tube throw the reference image and line of sight outof alignment with the gun bore axis. Thus, as the gunner keeps thesighting reference image and line of sight on a moving target, the gunis advanced automatically by the proper lead angle so that theprojectile should strike the target.

In order to introduce the superelevation corrections superelevationWeights and IOI are individually mounted in the front gimbal suspensionsystems of the gyro unit. The Weights are mounted on arms 582 and |93,respectively. Arm |82 is disposed in the plane of rotation of wheel 61and arm |83 is disposed in the plane of rotation of Wheel 11. When thegun is in a horizontal position the deflection of the gyro wheel 11caused by Weight IGI is a maximum. As the gun is elevated the effect ofweight IOI decreases, becoming zero when the gun is pointed to thezenith, (where the trajectory drop is zero). The Weight IUD for thetrain gyro 62 is directly above the gimbal axis when the gun bore ishorizontal. This construction makes it practicable for the two gyrounits 62 and 63 to interchange functions, so far as superelevation isconcerned, if the housing I1 in which the gyros are mounted is rotatedabout an axis parallel to the gun barrel. Such rotation or elevationaxis tilt occurs when a ship rolls or pitches. The superelevationcorrection is introduced independently of the lead angle. If the gunsight is stationary, the reference image is positioned according to thecorrection for superelevation alone. When the sight is moved, as infollowing a target, the gyro wheels are denected by additional mountscorresponding t0 the rates of movement. The resultant position of thereference image then represents a combination of superelevation and leadangle corrections.

Range adjustments are made in the sight by turning the range knob |85(Fig. 3). This ad-4 justment causes equal rotation of the two rangegears IDB and |01, one at each gyro unit. Each range gear causes itsassociated set of range springs 13-14 or 83-84 to move in or out andthereby offer more or less resistance to deec: tions of the gyro Wheels.When therange knob is turned to a lower range setting, the range springsare shifted toward the center and the resulting gyro deflections due tomovement of the gun sight case are small. Thus, the deflection of thereference image is small and the resulting 75 lead langle is relativelysmall. When the range knob is turned to a high range setting, the rangesprings are shifted away from the center and the gyro deflections arelarge. This gives a large lead angle as required for the greater range.The range setting also affects the superelevation oomponents. Thus whenthe range knob is turned to a low range Value the range spring positionsare such as to permit small deflections of the gyros due to thesuperelevation weights. This gives a small superelevation component.When the range knob is turned to a high range value, the range springspermit larger deflections of the gyros due to the superelevation weight.This gives a larger superelevation component as required for'the greaterrange.

Thus it will be noted that the range iire control datum is introducedinto the sight by manual adjustment of knob It. The target velocity recontrol data are introduced into the sight by therate-of-turn-indicators 62 and E3. The superelevation re control dataare introduced into the sight by the superelevation weights I3@ andlill.

As indicated in Fig. 3 batteries S3 and 98 are located in housing i8which may be placed within stand 22 of the gun (Fig. 5)

In explaining the operation of the above-described sighting arrangement,it will be assumed that the interior and exterior ballistics of the gunand projectile have been determined, that range tables are available,that all of the characteristics of the gun and thcprojectile are known,and that a selected stationary target is depressed from the supportingplane. For purposes of simplicity it will be assumed that there is notrunnion or elevation axis tilt and that the target position is suchthat a hit is mathematically predictable ii the line oi iire ishorizontal. Under that assumed condition, gravity is exercising itsmaximum effect on the projectile. The

sight is so adjusted under this condition that superelevation weight lGithen exercises maximum turning moment on shaft S2. The sight is then sadjusted that sliding contact il is at such a point on resistor 95 as tocause to be applied to the Vertical delecting plates of the cathode raytube a voltage appropriate to align the peep 35, the reference image,and the target. The line of sight is then on the target, althoughdisturbed from the line of lire by the amount of the superelevationcorrection, and a hit should be scored when the gun is fired. Theoperation of the superelevation weight is such as to disturb the line ofsight to a maximum extent for any given range under this condition. Nowlet it be assumed that fire should be directed to another stationarytarget which is located immediately above and at 90 degrees of elevationwith respecthe gun. Under that condition the turning moment of weightlill about the gimbal frame of wheel l is at a minimum and the contactAll is at the center or grounded point of resistor '35. Under thatcondition the reference mark is vertically centered and the line ofsight is not disturbed at all.

The distance from the gun to the target may be regarded as iniiinitewith respect to the distance between casing Il and the gun. Betweenthese two terminal conditions (i. e. when iiring on stationary targetsbetween the zero and 90 degrees of elevation) one component of thevoltage appearing between conductor 52 and ground is trigonometricallyfunctionally related to and varies as the. cosine of the angle ofelevation. As indicated, the range adjustment for both superelevationand lead angle is provided by knob H15 and the mechanisms actuated bythat knob.

In practice, the ballistics of the gun and the projectile are obtainedfrom range tables. The iire control problem is capable of mathematicalsolution and the characteristics of the train and elevation rate gyrounits 62 'and 63, the r-ange adjustment mechanism, the potentiometers 65and 56, the sources 93 and 98 and the cathode ray tube 23 aremathematically determinable, so that specific second parameters are amatter of individual engineering design and depend upon the specificcharacteristics of the system to be used, as will be clearly understoodby those skilled in the art.

The operation of the superelevation weight |00 will become clear if itbe assumed that the supporting frame on which the gun and sight aremounted turns by degrees about the gun trunnion or elevation axis. Inthat case, the superelevation correction voltage is applied to plates i5and :ill and the train gyro unit 52 performs the function of providingthe superelevation correction. Under that assumed condition weight |00would be asserting its maximum turning moment about gimbal frame $9. Atzero degrees of pitch weight il controls theI superelevation correctionwhile at 90 degrees of pitch weight |99 controls the superelevationcorrection. Between these two terminal conditions, both weightscooperate to supply the required superelevation corrections.

When both bore and trunnion axes are horizontal, the train weight has noeffect, while the elevation weight has maximum effect. This is apparentfrom the fact that the train weight is on a vertical line through itsgimbal shaft, and therefore has no leverage and cannot apply a turningeffort or torque. At the same time, the elevation Weight has its maximumleverage, and thus applies its greatest torque.

When the trunnion axis tilts, leverage is acquired by the train weightand lost by the elevation weight, and each gyro unit computes part ofthe superelevation. The sight construction is such that the resultantelectrical potentials caused by the superelevation weights displace thereference mark only in a vertical plane, regardless of the trunnion-axisinclination.

As the bore elevates above the horizontal, both weights lose leverageand their eects decrease, becoming Zero when the bore axis is vertical.The range springs resist the torque applied by the 'weights just as theyresist the precession due to tracking. Since the springs are most stiffwhen adjusted for short ranges, the gimbal-shaft rotation caused by theweights varies in the same manner as superelevation, namely: (l) maximumfor horizontal firing and decreasing as target elevation increases; (2)maximum for long ranges and minimum for short ranges. Thus, with theweights properly designed and adjusted for a particular gun,superelevation compensation is automatically introduced at any elevationand range, and theV correction is independent oi trunnion or elevationaxis tilt. Since the lead angie computation s also correct for any valueof trunnion tilt, it is evident that no separate trunnion-tiltcorrections are needed.

Let it now be assumed that iire is being directed cn a moving targetsuch as an airplane. The superelevation correction is functionallyrelated to the position of the airplane and not to its Velocity and thearrangement for applying that correction has already been described. Theoperator swings Vthe gun and sight in tracking the moving airplane. GyroWheels 61 and 11 precess by amounts functionally related to the trainand elevational components, respectively, of the target velocity. Levers85 and 8l are accordingly displaced by the operation of unit 62 and itsrange springs and unit 63 and its range springs, respectively, by suchan amount as to cause to be applied to the cathode ray tube 23 voltagesrespectively proportional to the product of target azimuthal velocityand range and to the product of target elevational Velocity and range,respectively. Thus the lead angle corrections are provided.

Although it has been assumed in the preceding discussion that theprojectile velocity remains constant for all ranges, this is of coursenot exactly true and the decreasingT projectile Velocity with increasedrange is a factor which should be considered in a rate sight. As therange increases the average velocity of the projectile decreases and thelead angle should be increased slightly with increased range tocompensate for this loss of projectile velocity. This correction issometimes called a time of iiight correction, and should be consideredin the range setting device hereinabove described. As is obvious tothose skilled in the art this is accomplished by appropriate shaping andadjustment of the range springs. Thus, the nal correction made in theposition of the reference image in the sight by the adjustment of therange control knob is functionally related to time of night, which, asindicated, does not vary precisely linearly with range.

While there has been shown what is at present considered to be thepreferred embodiment of the present invention, it will be obvious tothose skilled in the art that various changes and modications may bemade therein without departing from the true scope thereof, and it is,accordingly, intended in the appended claims to cover all such changesand modications as fall within the true scope of the invention andwithout the proper scope of the prior art.

The invention herein described may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

1. In combination with a gun movable in planes of elevation and train, agunsight adapted to move in unison with said gun and comprising acathode-ray oscilloscope having vertical and horizontal cathode-raydeflecting plates for providing a reference mark, optical means forimposing an image of said mark in the line of sight of a gunner wherebythe image may be moved simultaneously with a target, a first rategyroscope responsive to movement of said gun in train including agyroscope rotor mounted for spin in e, plane normal to the plane oftrain of said gun, a second rate gyroscope responsive to movement ofsaid gun in elevation including a gyroscope rotor mounted for spin in aplane normal to the plane of elevation of said gun, means mounting saidrotors for freedom of movement about parallel axes each normal to theaYis of spin of its respective rotors whereby the rotors of said lrstand second gyroscopes will be free to turn respectively about said axesin a direction determined by the direction of movement of said gun intrain and elevation and through an angle the magnitude of which isproportional to the rate of movement of said gun in train and elevation,potentiometers for the train and elevation gyroscopes each having amovable contact, means connecting said contacts respectively to thehorizontal and vertical deecting plates of said cathode-rayoscilloscope, and means for moving said contacts responsive to themovement of their respective rotors about said parallel axes wherebysaid image will be displaced in a plane normal to said line of sight ina direction and an amount proportional to the direction and rate ofmovement of said gun in elevation and train to provide a proper leadangle when optically tracking a target.

2. A gun sight comprising means for providing a sight line, an azimuthrate gyroscope mounted for movement with said sight line means and forresisted precession in response thereto, an elevation rate gyroscopesimilarly mounted, an azimuth potentiometer controlled by precession ofsaid azimuth gyroscope, an elevation potentiometer controlled byprecession of said elevation gyroscope, a cathode ray tube, rate signalsobtained from said two potentiometers being applied across two pairs ofopposite beam deeoting plates of said tube to provide indications of therates of angular movements of said sight line means relative to a stablereference in space, means for representing said indications as asighting reference in the sight line, means for adjusting the resistanceto gyroscope precessions in accordance with a chosen targets range, andmeans cooperating with said gyroscopes to provide additional angulardeflections thereof about their precession axes in accordance with thesight line means angle of elevation and elevation axis tilt, therebyproviding for azimuth and elevation lead and superelevation compensationin the position of said sighting reference when movements of a targetare tracked.

3. A gun sight comprising means for providing a sight line, an azimuthrate gyroscope mounted for movement with said sight line means and forresisted precession in response thereto, an elevation rate gyroscopesimilarly mounted, an azimuth potentiometer controlled by procession ofsaid azimuth gyroscope, an elevation potentiometer controlled byprocession of said elevation gyroscope, a cathode ray tube, rate signalsobtained from said two potentiometers being applied to the beamdelecting means of said tube to provide indications of the rates ofangular movements of said sight line means relative to a stablereference in space, means for representing said indication as a sightingreference in the sight line, and means for adjusting the resistance togyroscope precessions in accordance with a chosen targets range, therebyproviding for azimuth and elevation lead compensation in the position ofsaid sighting reference when movements of a target are tracked.

4. A gun sight comprising means for providing a sight line, an azimuthrate gyroscope mounted for movement with said sight line means and forprecession in response thereto, an elevation rate gyroscope similarlymounted, an azimuth variable electrical signal means controlled byprecession of said azimuth gyroscope, an elevation variable electricalsignal means controlled by precession of said elevation gyroscope, andan electrical signal responsive indicator means, rate signals obtainedfrom said two signal means being applied to said indicator means toprovide indications of the rates of angular movements of said sight linemeans relative to a stable reference in space, and means forrepresenting said indications as a sighting reference in the sight line,said indications thereby providing for azimuthA and elevation leadcompensation when movements of a, target are tracked.

5. A gun sight comprising means for providing a sight line, a rategyroscope mounted for movement with said sight line means and forresisted precession in response thereto, a potentiometer controlled byprecession of said gyroscope, a cathode ray tube, rate signals obtainedfrom said potentiometer being applied across beam deiiecting means ofsaid tube to provide indications of the rates of angular. movements ofsaid sight line means relative to a stable reference in space, means forrepresenting said indications as a sighting reference in the sight line,and means for adjusting the resistance to gyroscope precessions inaccordance with a chosen targets range, thereby providing forappropriate lead compensation in the position of said sighting referencewhen movements of a target relative to the gun sight are trackedtherewith.

6. A gun sight comprising means for providing a sight line, a rategyroscope mounted for movement with said sight line means and forprecession in response thereto, a variable electrical sigvnal meanscontrolled by precession of said gyroscope, an electrical signalresponsive indicator means, rate signals obtained from said'signal meansbeing applied to said indicator means to provide indications of therates of angular move- 30 ments of said sight line means relative to astable 112 reference in space, and means for representing saidindications as a sighting reference in the sight line, said indicationsthereby providing for appropriate lead compensation when movements of atarget relative to the gun sight are tracked therewith.

PHILLIP ROOD WHEELER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTSy Number Name Date 1,936,442 Willard Nov. 21, 19332,231,929 Lyman Feb. 18, 1941 2,399,726 Doyle et al May 7, 19462,405,068 Tear et al July 30, 1946 2,407,191 Tear et al. Sept. 3, 19462,418,158 Bruce Apr. 1, 1947 2,433,843 Hammond et al Jan, 6, 19482,455,963 Wheeler Dec. 1,'4, 1948 2,459,206 Wheeler Jan.' 18.19492,464,195 Burley et al. Mar. .8,'1949 2,467,831 Johnson Apr. 19,19492,504,168 Wheeler Apr. 18,195

FOREIGN PATENTS Y;

Number Country Date` f' 107,304 sweden May;4 ,'19f13 749,767 France May'15, 1,933

